Generally, a refrigerator comprises a freezing chamber and a cooling chamber. A vegetable compartment is additionally provided at a specific location in the cooling chamber so as to store vegetables and fruits in a more fresh state.
Many factors, such as temperature, humidity, environmental gas, microbe, light and etc., do influence on freshness of vegetables. Because vegetables do breathing and transpiration continuously, it is necessary to restrain the breathing and the transpiration in order to maintain the freshness of vegetables. Most vegetables, except for some kinds of vegetables that have trouble at low temperature, restrain the breathing at low temperature and the transpiration at high humidity.
For this reason, the refrigerator is provided with the vegetable compartment with an independent space from the cooling chamber, so as to store vegetables in a fresh state for a long period. The vegetable compartment is kept in adequately low temperature and as high humidity as possible. In other words, the temperature and the humidity in the vegetable compartment are maintained adequately for keeping the freshness of vegetables in the vegetable compartment high.
Meanwhile, research of a method of maintaining the freshness of vegetables by using the light (another influential factor concerning the freshness of vegetables) is being pursued. Relatively strong light has a bad influence of promoting color change and transpiration of vegetables, and relatively weak light has an effect of improving the maintenance of the freshness of vegetables. Also, weak light restrains chlorophyll degradation of green leafy and stem vegetables, and has an effect of keeping in vitamin C.
A conventional refrigerator having a vegetable compartment using light will now be described with reference to FIG. 1.
The conventional refrigerator illustrated in FIG. 1 is a refrigerator disclosed in Japanese Patent Laid-open Publication No. 9-28363. A refrigerator 10A is provided with an irradiation device 23A which irradiates weak light to a vegetable box 20A, so as to prevent decrease of chlorophyll concentration of green leafy and stem vegetables, and resultantly prevent deterioration of the quality of leafy and stem vegetables.
An illuminating lamp 29A is provided over the vegetable box 20A. When the vegetable box 20A is opened, the illuminating lamp 29A emits light to allow a user to easily see the vegetables stored in the vegetable box 20A. When the vegetable box 20A is closed, the irradiation device 23A irradiates weak light to the vegetable box 20A to prevent deterioration of quality of green leafy and stem vegetables.
Japanese Patent Laid-open Publication No. 11-159953 discloses a refrigerator provided with the irradiation device 23A which is embodied by a light emitting diode (LED) which emits light within a visible light region. Accordingly, heat generation from the irradiation device 23A is minimized, rise of temperature in a storage space 21A of the vegetable box 20A is prevented, and irradiating efficiency is increased as compared to other irradiation devices.
Japanese Patent Laid-open Publication No. 2005-49093 discloses a refrigerator provided with a red LED which emits light of a wavelength of about 660 nm to green leafy and stem vegetables.
Japanese Patent Laid-open Publication No. 2005-65622 discloses a refrigerator provided with several partitioned vegetable compartments and irradiation devices which irradiate light of adequate wavelengths for kinds of vegetables stored in the vegetable compartments. More particularly, a red LED, a blue LED and a green LED are used for selectively combining emitting colors according to the kinds of vegetables.
FIG. 2 shows the irradiation device provided at the vegetable compartment in the conventional refrigerator.
As shown in FIG. 2, an irradiation device 1 of the conventional refrigerator (which is disclosed in Japanese Patent Laid-open Publication No. 11-159953) is embodied by an LED which emits weak light within a visible light region, thereby preventing deterioration of quality of green leafy and stem vegetables.
However, the above conventional refrigerator has problems as follows.
While the vegetable compartment generally has a hexahedral storage space, light emitted from the light source (especially, the LED) goes straight with a constant irradiation angle. Therefore, light emitted from the light source cannot be irradiated to some inner portions of the vegetable compartment, especially, by an irradiating distance and obstacles. In other words, the conventional refrigerator has a shortcoming that light emitted from the light source cannot be effectively irradiated to all vegetables.
Also, light emitted from the light source is not entirely used for keeping the freshness of vegetables. This is because the vegetable box is generally made of transparent or white material, through which the irradiated light can mostly penetrate.
Also, because the irradiation device is mounted in the state of protruding toward the vegetable compartment, the irradiation device may be broken when moving the vegetable box or food storage containers.
Also, a short may occur by damage of an electronic substrate of the irradiation device due to moisture of the refrigerator.
Also, the emitting colors from the three color (red, blue, green) LEDs can be selectively combined, but it is not accurate that which of the red LED, the blue LED and the green LED respectively are effective to which foodstuffs. Therefore, such an irradiation device is not effective to the maintenance of the freshness of the stored foodstuffs and the prevention of the chlorophyll degradation.
Further, means for selecting the emitting color from the three color LED is provided, but the selecting means is not practical due to lack of accurate information that which emitting color is most adequate for which foodstuffs.
Although it is found that which emitting color is most effective to which foodstuffs by experiments, it is very difficult for the user to remember this information one by one to select the emitting color, or it is very troublesome for the user to search this information before selecting the emitting color.
Also, regarding the foodstuffs, the relationship of which with the emitting color is not experimentally found, the user cannot determine which emitting color is adequate for the foodstuffs and cannot be confident whether the user-selected emitting color is adequate for the foodstuffs or not. Thus, the user comes to distrust the irradiation device.